> Doesn't this just mean that Apple, Google, etc., are rent seeking?
I don't think so. Its subjective, of course, but they are consistently adding value to their platforms and services.
> It's mostly the same with apps that are copied into OS features. What entitles Apple, Google, etc., to the value of that idea beyond some kind of might makes right argument?
A patent is a license from the government to extract value from your idea for a period of time. If your idea meets the criteria for a patent, I encourage you to patent it. If your idea doesn't meet the criteria, tough. Apple and Google are then entitled to the value for execution, whereas you're entitled to nothing.
> They're big and they spend money on regulatory capture and legal battles, so that alone entitles them?
While a small amount of regulatory capture and legal battles have contributed to the development of Apple and Google's ecosystems, what entitles them to their value is the moat they've created through effort (engineers * time).